Die for drawing metal wire rod, and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-10478877-B2
Application number	US-201515304608-A
Country	US
Kind code	B2
Filing date	Mar 25, 2015
Priority date	Apr 18, 2014
Publication date	Nov 19, 2019
Grant date	Nov 19, 2019

Abstract

Provided are a metal wire rod drawing die that has a longer life than conventional dies and that can prevent damage to a metal wire rod surface and a method for manufacturing the die. In a metal wire rod drawing die ( 1 ), a die hole ( 2 ) for inserting a metal wire rod is formed. Where Ra 1 represents a surface roughness of an inner surface of the die hole from a bearing section ( 2 b ) to an approach section ( 2 a ) corresponding to an area reduction rate of 30% in an axial direction of the die hole, Ra 2 represents a surface roughness of the inner surface of the die hole from the bearing section to the approach section corresponding to the area reduction rate of 30% in a direction orthogonal to the axial direction of the die hole, and Ra 3 represents a surface roughness of an inner surface of the bearing section of the die hole in the axial direction of the die hole, the Ra 1 , the Ra 2 , and the Ra 3 satisfy a relationship represented by 0.14 μm>Ra 2 >Ra 1 >Ra 3.

First claim

The invention claimed is:

1. A metal wire rod drawing die with a die hole formed therein for inserting a metal wire rod, the die being characterized in that the die hole comprises an approach section tapered in a direction in which the metal wire rod is inserted and a bearing section having a constant inner diameter located at a subsequent stage to the approach section; and where Ra 1 represents a surface roughness of an inner surface of the die hole from the bearing section to the approach section corresponding to an area reduction rate of 30% in an axial direction of the die hole, Ra 2 represents a surface roughness of the inner surface of the die hole from the bearing section to the approach section corresponding to the area reduction rate of 30% in a direction orthogonal to the axial direction of the die hole, and Ra 3 represents a surface roughness of an inner surface of the bearing section of the die hole in the axial direction of the die hole, the Ra 1 , the Ra 2 , and the Ra 3 satisfy a relationship represented by the following formula:
0. 14 μm>R a 2>R a 1>R a 3.

2. A method for manufacturing the metal wire rod drawing die according to claim 1 , the method being characterized by comprising a sizing step of polishing the inner surface of the die hole for inserting a metal wire rod to a predetermined diameter and a polishing step of polishing the inner surface of the die hole by abrasive flow machining after the sizing step.

3. A method for manufacturing the metal wire rod drawing die according to claim 1 , wherein the Ra 1 , the Ra 2 , and the Ra 3 satisfy a relationship represented by the following formula:
0. 11 μm>R a 2>R a 1>R a 3.

4. A method for manufacturing the metal wire rod drawing die according to claim 1 , wherein the Ra 1 and the Ra 3 satisfy the following formula: Ra 1 ≤0.0884 μm and Ra 3 ≤0.0508 μm.

Assignees

• Bridgestone Corp

Inventors

• Saito Takayuki

Classifications

• B21C3/02 Primary

  Dies; Selection of material therefor; Cleaning thereof · CPC title

• B21C1/02

  Drawing metal wire or like flexible metallic material by drawing machines or apparatus in which the drawing action is effected by drums · CPC title

• B24B31/116

  using plastically deformable grinding compound, moved relatively to the workpiece under the influence of pressure · CPC title

• C22C29/02

  based on carbides or carbonitrides · CPC title

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title